The SMR family comprises four base models designed as CW generators with pulse modulation capability. The four models have a common lower frequency limit of 1GHz and provide frequency coverage up to 20 GHz (SMR20), 27 GHz (SMR27), 30 GHz (SMR30) and 40 GHz (SMR40). The lower limit can be expanded to 10 MHz by the optional Frequency Extension 0.01 GHz to 1 GHz (SMR-B11).

Offering an excellent price/performance ratio, each of the four base models is ideal for the user wishing to enter the field of microwave testing at an affordable price. Should the measurement tasks become more demanding, the base models can be upgraded any time by means of options to give an AM/FM signal generator or a synthesized sweep generator featuring fast, fully synthesized, analog ramp sweep.

The SMR stands out from other generators for its excellent spectral purity. Advanced frequency synthesis with fractional-N divider makes for low SSB phase noise and high spurious suppression, both of which are for example prerequisites for reliable receiver measurements. Modern microwave filters in the output path of the instrument ensure excellent harmonics suppression. This is necessary to obtain conclusive results in scalar network analysis measurements.

Microwave signal generators are frequently used for calibrating test receivers. This task calls for a highly accurate and stable output level settable with high resolution. This is ensured by a high-precision, frequency-response-compensated level control for levels higher than 20 dBm. The setting range can be extended to 130 dB with the optional RF Attenuator SMR-B15 or SMR-B17.

The crystal reference built in as standard ensures an accurate, low-drift output frequency. The SMR can be fitted with the optional OCXO Reference Oscillator SMR-B1 to satisfy the most stringent requirements in terms of accuracy and aging.

All microwave test setups involve high losses caused by the use of long cables, power dividers, directional couplers and RF relays. Expensive microwave amplifiers are usually the only means to remedy this. But not with the SMR: the high output power provided by all models eliminates the need for such a costly component.

The standard frequency resolution of 1 kHz of the SMR offers a comfortable margin for most applications, for example frequency response measurements in the laboratory and in production and servicing. To satisfy more stringent requirements, e.g. for scientific applications and research, the SMR-B3 option is available to improve frequency resolution to 0.1 Hz.

Pulse modulation is still the most important modulation mode for microwave applications. Each of our base units is, therefore, equipped with a high-quality pulse modulator. The on/off ratio is better than 80 dB, the rise/fall time shorter than 12 ns. Pulse widths of up to 25 ns are possible.

These guaranteed values illustrate that the SMR is the ideal generator for use in the development, production and maintenance of radar equipment.

SMR-B14 is an ideal complement to the pulse modulator. It generates single and double pulses with pulse frequencies up to 10 MHz. The pulse generator can also be triggered externally and operated in the external gate mode. The pulse width and delay are user-selectable over a wide range.

The 20 dB level sweep allows, for example, amplifier or mixer compression to be determined.

SMR-B5 added to the base models turns them into fully-fledged signal generators with AM and FM modulation capability. The option also includes an LF generator for sinewave and squarewave signals from 0.1 Hz to 10 MHz. The FM modulator has a modulation bandwidth from DC to 5 MHz. Digital frequency shift keying (FSK) is possible with data rates from 0 Hz to 2 MHz.

All modulation modes of the SMR can be combined. This allows the generation of complex modulation signals for modern communication and location systems. The combination of pulse modulation and FM simulates Doppler effects or chirp signals. Simultaneous AM and pulse modulation provides the types of signal occurring in pulse radar applications with rotating antenna. The combination of FM and AM can be used to check fading effects of FM receivers.

The analog ramp sweep mode corresponds to the analog sweep of classic sweep generators except that the sweep is fully synchronized over the complete range. In this way, the excellent frequency accuracy of digital step sweeps is achieved on the whole, and this at much higher sweep rates of min. 600 MHz/ms at frequencies >2 GHz. In conjunction with scalar network analyzers or suitable spectrum analyzers, realtime adjustment of microwave filters can be performed, for example.

To mark important frequency ranges such as filter bandwidths or the position of attenuation poles, the SMR has 10 user-selectable frequency markers which can be output as pulse markers at the marker output (TTL level) or alternatively modulated on the RF level as level markers (level reduction of 1 dB).

Vector signal generators such as the SMIQ generate all types of digitally modulated signals up to 6.4 GHz. To generate signals up to 40 GHz, the SMR offers upconversion capability by means of the IF input option. A typical application is shown by the figure above. The I/Q Modulation Generator AMIQ supplies the I and Q signals (1) required for modulating the Vector Signal Generator SMIQ.

The modulated RF signal of the SMIQ (2) is applied directly to the IF input of the SMR. At the RF output of the SMR, the converted, digitally modulated signal of the SMIQ is brought out (3). In the example illustrated above, the selective circuits of the DUT separate the wanted signal from unwanted components generated during upconversion. Alternatively, suitable external bandpass filters can be used.